Moving stairway handrail control



July as, 1953 w. P. EAMES 2,646,868

MOVING STAIRWAY 'HANDRAiL CONTROL Filed July 12' 1950 WITNESSES: INVENTOR William F. Eomes.

Patented July 28, 1953 MOVING STAIRWAY HANDRAIL CONTROL William F. Eames, Westfield, N. .L, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania I Application July 12, 1950, Serial No. 173,373

1 The present invention relates to moving stairways and, more particularly, to a device to control the stairway movement in the event of improper operation of the handrail of the stairway. Stairways of the type under consideration comprise, generally, a connected series of moving steps, and a handrail moving in synchronism therewith which is to be grasped by the pas-' sengers during their travel on the stairway. Such a stairway is disclosed in Patent No. 2,071,- 813, issued February 23, 1937 to Bouton, et al.

The handrail itself is usually a molded rubber or synthetic rubber product that is cut to the desired length, spliced and vulcanized into an endless belt extending over suitable sheaves, at least one of which is usually driven by the electric motor constituting the motive means of the stairway. The handrail and driving sheave are in frictional engagement, and since the handrail is subject to aging, stretch and wear,"any one of which may lower the traction between the handrail and the driving sheave, a point may be reached where a small increase in load on the hand rail may cause it to slip excessively on its driving sheave, or even come to rest. This is not serious so far as passengers on the stairway are concerned, but it is an abnormal operation causing excessive wear on the handrail as it slips on its driving sheave, and such wear, of course, is cumulative. I

Accordingly, it isan object of the'invention to provide a device for a moving stairway handrail which will be effective to stop the stairway in response to the handrail movement falling out of synchronism with the stairway by a predetermined amount or at a predetermined'rate.--

According to the invention, the speed of the handrail is matched against the speed of its driving sheave and any differential between such speeds, of a predetermined amount or above a predetermined rate, will actuate a circuit-controlling device to control the stairway driving means, or energize a suitable signal device to. indicate that slippage exists. a

{Figure 1 is a schematic diagram of amoving stairway, including a handrail, to which the invention is applicable, and' Fig. 2 is a schematic showing, on anenlarged scale with respect to Figure 1 of a preferred mechanism for practicing the invention.

Referring to Fig. 1, a moving stairway may comprise an endless chain 2, the links of which pass over sprocket wheels 4, one of which is driven by a motor 5. An endless series of steps 6 is suitably carried by the chain and are pro- 2 Claims. (Cl. 19816) til I handrail l0.

2 vided with rollers riding on trackways to maintain the steps in the desired passenger-carrying position.

A handrail I is provided for the convenience of the passengers, and comprises an endless flexible belt usually of substantially U-shape'in lateral section for embracing a guiding surface (not shown) to maintain the handrail upper run substantially parallel with the movement of the passenger-carrying steps. The handrail also passes over guiding sheaves 1 and 8, and a driv-p ing sheave l2 which is rotated in synchronism with the stairway movement by a sprocket wheel M and sprocket chain I5 driven from the drive shaft of the step chain 2. v

Referring to Fig. 2, a fraction wheel l6issuitably mounted to be rotated by the driving sheave i2 and carries with it a pinion gear l8 constituting part of a difierential gearing assembly. A

friction wheel is suitably supported to ride upon the inner surface of the handrail l0 and carries with it a gear 22 which drives the ring gear 24 of the differential which, in turn, car-' ries the idler spur gears 26. The output of the differential is a pinion With the structure described, it should be apparent that the input l8 of the differential gearing assembly will be driven in accordance with the rotation of the driving sheave l2, andthe input comprising the ring gear 24 will be driven in accordance with the movement of the same, no motion will be imparted to the output shaft 30, but upon the occurrence of any differential movement, such as may be caused by a slip in the frictional engagement between the wheel l2 and the handrail ID, the differential movement will be imparted to shaft which will then revolve in proportion to such differential movement.

A coiled spring 38 surrounds the shaft 30 and i normally forces the clutch facing 34 into contact with clutch plate 40 which, in turn, is mounted, Actuation of the clutch periodically is accomplished by means of a linkage,

on a threaded shaft 42.

44 comprising a pivoted lever 46 having a bifurcated lower end terminating in rollers which ride in a slot 48 in the clutch plate 32. The lever 46 is periodically actuated through lever 53 which terminates in a roller 52 which rides upon the face of the driving sheave l2 and intermittently, at least one per revolution of sheave l2, rides is" having a splined shaft upon which is slidably If both of these movements are theupon a cam surface 54 to move the arm 50 to the left and hence disengage the clutch elements 32 and 49 to break the driving connection with shaft 42.

A traveling nut 56 rides along the threaded shaft 42 in accordance with the extent of rotation of the shaft when the clutch faces are in engagement. The nut 56 has a lower extension 51 which is preferably bifurcated or notched to ride along a guide bar 58 so that turning of the nut is prevented as its moves along the threaded shaft 42. A pair of levers 59 are each pivoted at one end 60, and each is of fork shape to embrace the guide bar 58 and has free ends, on opposite sides of the shaft 42, provided with anti-friction rollers 6| riding on a face of the nut. A spring 62 biases the levers 59 toward the nut, and stops 63 on bar 58 limit the movement of the levers toward each other. With the clutch elements 32 and 46 engaged, movement of the nut 56 in either direction will be a measure of the amount of slippage or differential movement between the driving sheave l2 and the handrail i9. rhe thread on shaft 42 is of a pitch sufficiently steep that lateral movement of the nut, without rotation because of guide bar 58 and extension '1, will rotate the shaft 42 when the clutch elements 32 and 46 are disengaged to permit centering of the nut to the position shown under the influence of levers 59 and spring 62, and at suitable points in the path of movement of the nut 56, switches or circuit-controlling devices 64 are disposed to be operated by engagement of extension 69- on the nut. These switches may be connected in the safety circuit of the driving motor of the stairway to open such circuit and stop the motor in the event the slippage is of a predetermined amount as measured by the travel of nut 56.

The rate of slippage is also a factor in determining whether or not the stairway should be shut down for repair to the handrail driving system. This is accomplished by the clutch and its periodic declutching operation, that is, if the amount of slippage or differential movement dur ing one revolution of the driving sheave I2 is not suficient to move the nut 56 into engagement with the operating handles of the switches 64, upon the next declutching operation the nut will be moved to its central position, as shown, under the influence of the biasing spring 62. However, when the clutch elements are in driving relation and the slippage is more than a desired amount during such period, the nut 12 will engage either of the operating handles of the switches 54, depending upon the direction of slippage, and the safety circuit to the stairway motor may be opened. The switches 64 preferably are of the snap-switch type which will require a stairway attendant to investigate the cause of the slippage and correct it before resetting the operated switch. However, for some applications, it may not be desirable to shut down the stairway, in which event the switches may be used to actuate a signal or alarm indicating that excessive slip has occurred. Also, although only one cam 54 on the driving sheave is shown, two or more may be considered desirable and the cam or cams may, of course, be on other parts of the handrail or stairway drive.

In accordance with the above-described structure, an unusually simple and effective means is provided for affording a control, or signal, in response to a predetermined differential movement between a stairway handrail and its driving sheave, at the point of frictional contact thereof, which will distinguish between slippage of an objectionable amount and an amount which is relatively inconsequential. Of course, in the case of a breakage of the handrail, such as caused by an improperly vulcanized joint, the control switches will act almost instantaneously, which is desirable. The device will be effective to reduce wear between the inner surface of the handrail and the driving sheave occasioned by undue slippage in that the stairway will be shut down until the slippage is corrected.

Quite obviously, variations of the structure shown and described will present themselves to those skilled in the art, and it is intended that the disclosure is only illustrated of one practicable embodiment of the invention.

I claim as my invention:

1. In a moving stairway includin a flexibly connected continuous series of movable steps and an electric motor for moving them at a constant speed, a flexible continuous handrail and means for moving it in synchronism with and substantially parallel to the movement of said steps including a sheave positively driven from said motor and in driving engagement with said handrail, a circuit controller for the circuit of said motor and actuating means therefor, difierential means responsive to relative movement between said sheave and handrail at the point of driving engagement for advancing said actuating means from an initial position toward'an opera tive position with respect to said circuit controller, and means for periodically returning said actuating means to its initial position including a releasable connection between said differential means and said actuating means.

2. In a moving stairway including a flexibly connected continuous series of movable steps and an electric motor for moving them at a constant speed, a flexible continuous handrail and means for moving it in synchronism with and substantially parallel to the movement of said steps including a sheave positively driven from said motor and in driving engagement with said handrail, a circuit controller for the circuit of said motor and actuating means therefor, difierential means responsive to relative movement between said sheave and handrail at the point of driving engagement for advancing said actuating means from an initial position toward an operative position with respect to said circuit controller includin a releasable clutch between said differential means and said actuating means, and means for releasing said clutch periodically in accordance with the rotation of said sheave.

WILLIAM F. EAMES.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,820,634 Simmons Aug. 25, 1931 2,010,122 Wikle Aug. 6, 1935 2,071,813 Bouton Feb. 23, 1937 2,221,403 Lindquist Nov. 12, 1940 2,399,685 McCoy May 7, 1946 2,417,780 Parvin Mar. 18, 1947 2,461,261 Drisko Feb. 8, 1949 

